Timber-roof structure



2 Sheets-Sheet 1.

Patented Oet. 13,1891

E. MOLLOY.

TTMRRR ROOT STRUCTURE.

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E. MOLLOY. TIMBER ROOF STRUCTURE.

110,460,981. Patented Oct. `13, 1891.

HMM Mol/0f f' a H: 1 fw!! wi Y UNITED STATES PATENT OFFICE.

EDMOND MOLIIOY, OF PHILADELPHIA, PENNSYLVANIA.

TIMBER-ROOF STRUCTURE.

SPECIFICATION forming part of Letters Patent No. 460,981, dated October13, 1891.

Application tiled March 3, 1891. Serial No. 383,788. (No model.)

fo all whom it may con/cern.:

Be it known that I, EDMOND MOLLOY, a citizen ot' the United States,residing in the city of Philadelphia,in the State of Pennsylvania, haveinvented a new and useful Improvement in Timber-Roof Structures, ofwhich the following is a clear and sufficient specification, referencebeing had to the drawings annexed to and forming `a part of thisspeciiication.

In timber-roof structures heretofore the supporting of the roof hasgenerally been done by trusses or braces, very little, if any, ot thestrain being intended to be upheld by the cover or roof proper itself.In this way many weighty and cumbrous truss structures intended tosupport the Weight of the roof have been employed, whereby the weight ofthe whole structure has been increased without any proportional increasein the strength of the roof.

In my device the main strength of the structu re is given by the springof the boards forming the roof-sheath themselves, which are so securedthat they form together benta practically homogeneous structure, whichis bent into the form of a bow, and I use the trusses chieiiy, orfrequently entirely, to give rigidity to this covering structure. I canmake these trusses for this purpose of an extremely light weight and canplace them at much greater distance from each other than could be donewere they used for the purpose of supports ofthe root` and for themaintenance of the weight of the roof structure. The use of the bowspringing timber cover of the roof and the rigidity-giving truss are,then, the essentials of my invention, the mechanical structure andthedetails whereof are described in the following part of thespecification, and shownin the drawings, in which- Figure 1 is across-section across the arch. Figure 2 is a longitudinal sectionthrough the highest portion of the arch on the line l 2 of Fig. l. Fig.3 is a plan view of the covering of the roof, a portion of the boardinghaving been broken away to show the structure beneath. Fig. 4 is anenlarged view of a portion of the structure shown in Fig. l, and Fig. 5an enlarged section of a portion ofthe structure as shown in Fig. 2.

The drawings of this application are drawn as far as possible to thescale of an operative structure, the size of the purlins and thicknessof the boards excepted, but are intended only to show the extremelightness with which the structure can be constructed, and are not, ofcourse, to be taken as limiting the device to the proportional sizes ofmaterial illustrated.

In practice I find the best way to construct my roof structure is toconstruct the trusses, 'and after the wall or other support B on whichthe sides ofthe roof are upheld are up to place these trusses thereon. Ind these trusses are most advantageously constructed of a bow portion Cand a Stringer D. As the main purpose of the bow portion is to giverigidity to the roof-cover, I preferably make the width very slight andthe height proportionately much greater. A convenient construction bywhich this is accomplished is thatshown in the figures. Employing threepieces placed one above the other and bent into a bow form in anyconvenient or customary manner, in order to show the extreme lightnesswith which such truss can be constructed but not to limit my invention,I

would say that where this preferred form ot bow-piece is used the threepieces composing it need not be over two by two each to give therigidity where the span of the arch is forty feet and the trusses areeight feet apart. The joints of the pieces composing the bow C can bebroken in various places. For the same object I prefer to construct theStringer D with the widest part in the direction of the height of thetruss, and when the stringer is composed of two pieces I generallysecure them together by placing scarfiug-piece D on top of the same,which I preferably arrange to give its greater width in the direction ofthe height of the truss.

To assist in giving rigidity to the truss, I generally connect thebowpiece and the yStringer by means of braces, which are preferably thediagonals @ab b. For convenience the diagonals a c Ct,&c.,are generallyplaced on one side of the bow-piece andstringer and the pieces h l1 l)b, ttc., on the otherside of the same. Between these diagonal braces, togive greater rigidity to the structure, I generally place a curved pieceE. This piece also is most advantageously made with the greate1 ICOwidth in the direction of the height of the truss. I generally need onlyextend this piece through the center portion of the truss,

ground and to mount them afterward, which,

on account of their eXtreme lightness, can be read-ily done, with endson the supporting sides B B of the building. On the top of these trussesI place the covering-timbers, which, on account of the arched form ofthe roof, the elasticity of the timbers forming the roof-covering, andthe homogeneousness into which they are Wrought, are practicallyselfsupporting and place the Weight of the covering almost entirelydirectly on the Walls B B.

I find that the roof-cover is constructed most advantageously of boards(which are ordinarily scant inch boards) running substantially in thedirection of the length of the trusses; but I do not limit myself toboards thus running, as any direction in which the spring of the boardand its lengthwise strength can be utilized to maintain the arch will beWithin my invention. I connect these boards into a homogeneous structureby securing them at suitable intervals to pieces running at angles withthem, and Where the span of the arch is too great for a single length oftimber to be used I break the joints of the boards at various ones ofthese cross-pieces, as is illustrated in Fig. 3.

In practice I find the most advantageous manner of constructing myinvented roof is, after the trusses or several of them are placed inposition,to fasten purlins c c c c, extending across them at suitabledistances apart. On these purlins, after they have been placed inposition, are secured the boards arranged to run at an angle With them,taking care to break the joints of neighboring boards at differentpurlins. I preferably arrange these purlins to run longitudinally withrespect to the arch, as shown in the drawings, and most advantageouslyrun the boards directly from the edge of the roof in the direction ofthe highest part of the arch and nail them fast in the ordinary mannerused for boarding curved surfaces, taking care, however, that theirnatural elasticity is not impaired.

In my construction it can be seen that the strain caused by the effortto flatten itself of the elastic homogeneously-connected-together bentroof-sheath is expended in producing (analogously to the strain upon thestring of a strung bow) a stretching strain upon the Stringer D, whichwill be rendered more rigid by the strain. This strain may be takendirectly from the roof-sheath at the lower part of the arch or betransferred in part at the various purlins to the piece C of each truss.The strain, however, upon the piece C will be a straightening strain andnot a horizontal or breaking one, and the whole or nearly the whole ofthe Weight of the roof-sheath Will besustained, without substantialhorizontal pressure upon the pieces C, directly from the sides B B. Thesheath is practically self-su pporting independently of the trusses.When, however, an unequal pressure is brought to bear upon any part ofthe roof-sheath, the tendency of an elastic sheath which is supported atitssides only would be to be depressed at the point of pressure and tobelly out at another point. To guard against such a defect, the rigidityneedful is given by the trusses, which, as has been before stated, areconstructed in such manner, before described, as Will best resist apressure brought to bear upon and tending to depress a single point ofthe sheath, and are not constructed to sustain the weight of theroof-sheath.

When the boards have been secured to the purlins, the roof may betreated in the same manner as roofs constructed in any manner bytinning, graveling, or otherwise.

While I have described with great minuteness and in particularmyinvented roof, even in some cases going into the details of the sizesof some of the timbers therein, I do not limit myself to the precisestructure shown and described, as many changes can be made thereinWithout departing from my invention.

What I claim, and desire to secure byLett-ers Patent, is-

l. The combination o f a homogeneous arched timber-roof sheathinghavingthe timbers forming the same connected together into a homogenous sheet,arched trusses in which the bow-piece is in the form substantially of anarc of a circle and which are provided With rigid stringer-pieces, andconnections uniting the said sheathing to the trusses, and supports onwhich said trusses are supported, substantially as described.

2. The combination of a homogeneous arched timber-roof sheathing,consisting of a series of boards running substantially in the directionof the circumference of the arch of the roof and secured to purlinsrunning substantially at right angles with said boards, arched trussesin which the bow-piece is bent into the form substantially of an arc ofa circle and which is provided with a rigid stringerpiece, connectionsuniting the said sheathing to the trusses, and supports maintaining thestructure, substantially as described.

3. 'Ihe combination,with a homogeneouslyconnected arched roof-sheathinghaving the timbers forming the same connected together into ahomogeneous sheet, of arched trusses consisting of a compound arch-pieceformed of several pieces one above the other, a straight timberStringer-piece having its greatest width vertical, and diagonalconnecting-pieces connecting the bow-piece and the Stringer,substantially as described.

IOO

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4, The combination, with a homogeneous arched timber-roof sheathinghaving the timbers forming the same connected together into ahomogeneous sheet, of arched trusses consisting of a compound arch-pieceformed 0f several pieces placed vertically above each' 5. Thecombination, in a timber truss for timber roofs, of a compoundarch-piece consisting ot' several pieces placed vertically above eachother, a straight horizontal strin ger, diagonals having their greatestWidth vertical and crossing on one side and the other of the Stringerand arch-piece, and a supplemental zo piece E, substantially asdescribed.

EDMOND MOLLOY.

Vitnesses:

MARK WILKs COLLET, GEO. W. REED.

